1. Field of the Invention
This invention relates generally to self aligning or articulated mounting assemblies for shaft seals to maintain a sealed condition between a seal seating end face of a housing and a rotary shaft extending from the housing generally normal to said end face. Specifically, the invention relates to face-type shaft seals that will accommodate non-orthogonal alignment between the seal seating face of a housing and the axis of a shaft projecting from the housing.
2. Description of Related Art
In seals of the type used in devices including a rotary shaft extending from an opening in a generally planar end wall of a housing which provides a radial seating face for the seal, it is desirable to maintain the axis of the shaft normal or orthogonally to a radial seating face of the housing to maintain full sealing contact between relatively rotating seal rings of the seal assembly. These seal rings generally include a wearable seal member, such as a carbon seal ring rotating with the shaft and having a radial face sealingly engaging and riding on an opposed radial face of a stationary seal ring in a casing or housing mounted on the shaft housing. Thus, the rotating and stationary seal members are inherently maintained in sealing engagement in a plane normal to the axis of the shaft.
However, in installations where the shaft is not orthogonal to the housing, as is often the case with adjustable pumps, and where the shaft or shaft bearings are worn, the sealing face of the stationary seal member may assume a different angularly offset plane. Such offsets cause uneven pressure at the sealing faces creating premature failure of the seal.
My U.S. Pat. No. 4,639,000 issued Jan. 20, 1987 discloses a seal assembly which will accommodate some nonorthogonal misalignment of the shaft and seating face of the housing by providing relatively tiltable engaging surfaces between the stationary seal ring or member and its surrounding casing or housing. However, in this seal the stationary seal ring abuts the casing, and thus limits the tilting.
In addition to this limitation in accommodating only slight misalignments, significant forces are required to effect the tilting, and the parts must be manufactured to relatively close tolerances.
It would therefore be an improvement in this art to substantially increase the tilting capacity, decrease the required tilting forces and increase the tolerance limits of the seal disclosed in my aforesaid U.S. Pat. No. 4,639,000.